1. Field of the Invention
The invention relates to a method and mechanism for reducing the shock load on an actuator when the output shaft of the actuator is slowed or approaches its limit of travel.
2. Description of the Related Art
Prior art methods of and mechanisms for reducing shock load on an actuator generally included (1) rubber limit stops, (2) friction clutches, and (3) compression spring mechanisms. However, rubber limit stops do not work effectively over a wide temperature range due to changes in the durometer of the rubber with temperature. Friction clutches that use disks of material that are compressed together are susceptible to wear and change in torque with use. Compression spring mechanisms generally include two compression springs and a lever attached and extending perpendicularly from the output shaft. The lever rotates with the shaft and contacts a compression spring when the output shaft reaches its angular limit of travel. The disadvantages of the compression spring mechanism, in addition to requiring more than one spring, include that it is difficult to achieve similar rates of deceleration for the output shaft as it reaches each of its angular limits of travel because difference of spring rates (rate of deflection with a given load) between the two compression springs.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention claimed.
This invention offers advantages over the prior art by providing a simple, inexpensive method for reducing the shock load on the drive of a rotary or linear actuator when the motion of the actuator output shaft is slowed, even to the point of stopping. This is referred to as bringing the actuator to a xe2x80x9csoft stop.xe2x80x9d Additionally, the invention may include a spring and this spring stores energy that may be used to maintain a force against elements that may be attached to the invention""s output shaft, such as a linkage, cable, or rod. This invention uses a single spring wherein the spring may be a torsion, ribbon or compression spring.